In zirconia-supported nickel catalysts, the influence of the ZrO 2 phase on the catalytic activity for CO 2 methanation has been investigated by TPD and TPR measurements. Ni/ZrO 2 catalysts with various amounts of the tetragonal ZrO 2 polymorph were prepared from amorphous Ni–Zr alloys by an oxidation–reduction treatment. The fraction of tetragonal ZrO 2 in the Ni/ZrO 2 catalysts increased with increasing nickel content of the amorphous alloy precursors. The methanation activity of Ni/ZrO 2 was strongly influenced by the ZrO 2 phase change. The tetragonal zirconia-supported nickel catalysts showed a higher turnover frequency for the methanation reaction and a greater CO 2 adsorption than the monoclinic zirconia-supported nickel catalysts.